Surgical intervention in the treatment of tumors usually involves the opening of surface tissues and excision of the underlying tumor. This excision often involves the removal of healthy tissue along with the tumor tissue to insure complete removal of the affected cells. Surgical procedures, while effective, leave scarring and wounds which are open to infectious complications, and often result in long recovery periods. Surgical intervention is often imprecise in accessing affected tissue and may damage tissue structures such as nerves, muscle, and bone to achieve access to the tumor. Consequently, minimally invasive medical procedures are of interest in many circumstances in order to reduce the trauma suffered by normal or healthy tissue.
Where devices are used to perform tissue biopsy or are manufactured for deep surgical access, such procedures generally use a tubular probe to penetrate body tissue to reach a target tissue for biopsy or treatment. These prior art devices for biopsy or cancer treatment require direct contact between a target tissue and a medical instrument. Therefore, during a biopsy or cancer treatment procedure, cancer cells may become dislodged leading to spread of the cancer cells. For example, withdrawal of the biopsy probe may leave a trail of displaced cancer cells in the wake of the withdrawn probe. During localized treatment of a tumor, cancer cells may be dislodged and moved sufficiently from the treatment area to avoid the negative effects of the treatment procedure, and dislodged cancer cells may be carried through the blood or lymph systems to lodge in locations remote from the original tumor.
Some prior art surgical instruments have been disclosed that use electrical energy to heat the instrument for cauterization purposes. For example, U.S. Pat. No. 5,578,030, issued to Levin, discloses a biopsy needle which use resistive heating of the needle to cauterize the path of the needle to prevent the spread of cancer cells. However, such devices can cause significant damage to healthy tissue when cauterizing, and in the case of the biopsy needle of U.S. Pat. No. 5,578,030, measures must be taken to protect the biopsied sample from the heat produced by the device.
Many other prior art devices use RP energy to cut or cauterize tissue, or to ablate tumor tissue. Most of these devices monitor tissue impedance to prevent the energy entering the tissue from exceeding a predetermine value. However, because the impedance of the tissue may vary over the area in contact with the probe, localized hot spots may occur causing damage to healthy tissue through fulguration, which is the explosive ignition of small amounts of combustible gases which have escaped from killed cells.
What is needed is a probe device which can be used in various embodiments to biopsy or treat a target tissue, and which uses RF energy to prevent the spread of cancer cells or infectious agents, during a biopsy or treatment procedure, without the danger of fulguration.